linux_dsm_epyc7002/drivers/base/power/resume.c
mochel@digitalimplant.org af70316af1 [PATCH] Add a semaphore to struct device to synchronize calls to its driver.
This adds a per-device semaphore that is taken before every call from the core to a
driver method. This prevents e.g. simultaneous calls to the ->suspend() or ->resume()
and ->probe() or ->release(), potentially saving a whole lot of headaches.

It also moves us a step closer to removing the bus rwsem, since it protects the fields
in struct device that are modified by the core.

Signed-off-by: Patrick Mochel <mochel@digitalimplant.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2005-06-20 15:15:12 -07:00

126 lines
2.4 KiB
C

/*
* resume.c - Functions for waking devices up.
*
* Copyright (c) 2003 Patrick Mochel
* Copyright (c) 2003 Open Source Development Labs
*
* This file is released under the GPLv2
*
*/
#include <linux/device.h>
#include "power.h"
extern int sysdev_resume(void);
/**
* resume_device - Restore state for one device.
* @dev: Device.
*
*/
int resume_device(struct device * dev)
{
int error = 0;
down(&dev->sem);
if (dev->power.pm_parent
&& dev->power.pm_parent->power.power_state) {
dev_err(dev, "PM: resume from %d, parent %s still %d\n",
dev->power.power_state,
dev->power.pm_parent->bus_id,
dev->power.pm_parent->power.power_state);
}
if (dev->bus && dev->bus->resume) {
dev_dbg(dev,"resuming\n");
error = dev->bus->resume(dev);
}
up(&dev->sem);
return error;
}
void dpm_resume(void)
{
down(&dpm_list_sem);
while(!list_empty(&dpm_off)) {
struct list_head * entry = dpm_off.next;
struct device * dev = to_device(entry);
get_device(dev);
list_del_init(entry);
list_add_tail(entry, &dpm_active);
up(&dpm_list_sem);
if (!dev->power.prev_state)
resume_device(dev);
down(&dpm_list_sem);
put_device(dev);
}
up(&dpm_list_sem);
}
/**
* device_resume - Restore state of each device in system.
*
* Walk the dpm_off list, remove each entry, resume the device,
* then add it to the dpm_active list.
*/
void device_resume(void)
{
down(&dpm_sem);
dpm_resume();
up(&dpm_sem);
}
EXPORT_SYMBOL_GPL(device_resume);
/**
* device_power_up_irq - Power on some devices.
*
* Walk the dpm_off_irq list and power each device up. This
* is used for devices that required they be powered down with
* interrupts disabled. As devices are powered on, they are moved to
* the dpm_suspended list.
*
* Interrupts must be disabled when calling this.
*/
void dpm_power_up(void)
{
while(!list_empty(&dpm_off_irq)) {
struct list_head * entry = dpm_off_irq.next;
struct device * dev = to_device(entry);
get_device(dev);
list_del_init(entry);
list_add_tail(entry, &dpm_active);
resume_device(dev);
put_device(dev);
}
}
/**
* device_pm_power_up - Turn on all devices that need special attention.
*
* Power on system devices then devices that required we shut them down
* with interrupts disabled.
* Called with interrupts disabled.
*/
void device_power_up(void)
{
sysdev_resume();
dpm_power_up();
}
EXPORT_SYMBOL_GPL(device_power_up);